Soap and surfactant residue which is retained on the skin after facial washing there-with has been shown to cause skin roughness, tightness and dryness. Surfactants such as alkyl ether sulfates, alkyl sulfates, alkyl benzenes sulfonates, and even amine oxides are potential skin irritants. Patch tests therewith confirm that they have the potential to irritate skin.
For a surfactant to have a negative effect on the skin, it may have to be absorbed to, and be retained on, the skin after washing. Indeed Imokawa and Mishima (Nahihi Kaishi 86 473-481 (1976)) showed that skin roughness was related to surfactant deposition. In studying the skin feel effects of surfactant deposition, soap was precipitated onto the skin by adding calcium and magnesium salts to the wash water (i.e. increasing water hardness).
In a clinical study using several consumers who washed their faces with a leading brand of soap in hard water (400 ppm), deionized water and soap, and hard water without soap, and deionized water without soap; it was demonstrated that facial washing with a leading brand of soap in hard water caused significantly more perceived tightness than washing with soap in deionized water. (Washing with soap and deionized water elicited some perceived tightness). No tightness or other skin feel characteristic was felt with either the hard water or deionized water without the soap. This study demonstrated that washing with soap generates tightness of the skin.
An in vitro study using wool fabric and laurate soap demonstrated that Ca++ and Mg++ salts that produce water hardness increase surfactant deposition and absorption of the soap to the wool fabric, a keratin substrate. Hence, the water hardness increases the binding of the laurate soap to wool and, by analogy to skin, decreases the ability to wash the soap off the wool or skin, which binds the soap surfactant in a manner similarly to wool. It is the removal of this soap residue from the skin which is one aspect of the subject matter of present invention.
Commercial facial cleansers, such as Noxema which is a white cream, and Olay Beauty cleanser, contain soaps as ingredients in their formulations which exacerbate the irritation problems associated with soap residues on the skin. The removal of soap residues after cleansing with soap has not been addressed in the prior art. However, moisturizers have been used to mask the negative skin sensations after washing with soap.
The prior art discloses assorted liquid cosmetic lotions for cleansing purposes, as disclosed in U.S. Pat. No. 3,011,950, wherein a minor amount of a nonionic or anionic surfactant is dissolved in the aqueous phase containing a water soluble polymer and an inert gas such as oxygen, nitrogen or compressed air, dispersed therein to give a sparkling effect. U.S. Pat. No. 4,323,468 discloses a make-up remover composition for face and eyes comprising an oil in water emulsion containing a nonionic, anionic or cationic surfactant, an extract of sarsaparilla, a preservative, and a citrate or phosphate or lactate buffer to maintain a pH of 4-8.5 and preferably 6-8. U.S. Pat. No. 4,533,545 discloses cosmetic compositions containing polyethylene glycol derivatives as thickeners in the presence of a nonionic, anionic, cationic or amphoteric surfactant. U.S. Pat. No. 3,956,951 discloses a method of shaving which comprises washing the face with soap and water, rinsing all the soap from the face, and rubbing the wetted skin with a water-soluble solid polyethylene oxide polymer wafer prior to shaving with a blade type razor. U.S. Pat. No. 4,412,943 discloses a shampoo containing an alkyl sulfate, ethylene diaminetetraacetate salts, and an acid such as citric acid. U.S. Pat. No. 3,748,276 discloses aqueous gel compositions for use in cosmetics containing a polyether polyol gelling agent. U.S. Pat. No. 4,140,656 discloses an anhydrous clear gel facial cleanser for removal of eye make-up containing mineral oil, phosphate esters and carboxy vinyl polymers such as a polymer of acrylic acid crosslinked with polyalkylene polyether (Carbopol by B. F. Goodrich Company). U.S. Pat. No. 4,360,451 discloses amphoteric surfactant gels containing an amphoteric surfactant, a polyoxybutylene--polyoxyethylene block copolymer, and water for use in facial cleansing bath and shower gels, shampoos and the like.
None of the prior art cosmetic compositions have addressed adverse skin effects of the soap residue retained on the skin, particularly the face, after washing with soap and water.
It has now been found that a liquid skin cleanser, particularly a facial rinse/skin conditioner formulation effective in removing both soap and surfactant residue from the skin and reducing skin irritation and negative sensations of skin dryness, roughness and tightness, consists of low concentrations of a nonionic surfactant as the sole surfactant, and an organic acid (or salt thereof) such as citric acid to adjust the pH to that of the human skin (4.5 to 6.5), and a major amount of water, preferably deionized water; which may be thickened with polyethylene glycol--150 distearate to a thick liquid or thickened with an acrylic acid polymer to form a gel, and preferably contains a preservative. One such material comprises 1,3-dimethylol-5, 5 dimethyl (DMDM) Hydantoin and disodium ethylene diaminetatraacetate (EDTA). Another is Germaben II, a product of Sutton Laboratories, Inc.
The use of a nonionic surfactant as one of the ingredients in a liquid detergent for cleaning fabrics is well known in the prior art as disclosed in U.S. Pat. Nos. 3,764,544; 3,959,163; and 4,206,070.
U.S. Pat. No. 3,915,633 discloses an aqueous prewash aerosol spray soil release composition for use with a detergent or soap in a laundering operation, consisting of 1-20% by weight of an organic acid, i.e. citric acid, 2-30% by weight of an anionic or nonionic surfactant, water and an aerosol propellant. Canadian Patent No. 1,086,178 discloses a liquid heavy duty laundry detergent composition containing 20-70% by weight of a soluble ethoxylated nonionic surfactant, 0.1-1.25% by weight of a polyacid, i.e. citric acid, and water/organic solvents, having a pH of 6-7.5.
Also disclosed in the prior art are mixtures of a nonionic surfactant and polyacrylate thickeners in aqueous dishwashing detergent formulations as disclosed in U.S. Pat. Nos. 3,950,260 and 4,226,736.
U.S. Pat. No. 4,501,680 discloses acidic liquid detergent compositions for cleaning ceramic tiles without eroding grout between them, comprising a minor proportion of glutaric acid and a lesser amount of phosphoric acid to provide a pH of 3-5, a minor amount of an ethoxylated fatty alcohol, a minor amount of a diethylene glycol monoalkyl ether, and a major amount of water.
U.S. Pat. No. 4,172,140 discloses an antimicrobial composition for inhibiting the growth of microorganisms in an aqueous fluid medium comprising as the active ingredients, an admixture of 1,3-dimethylol-5,5 dimethyl hydantoin and disodium ethylene diaminetetraacetate, for use in metal working fluids, cutting oil fluids, coolants, lubricants, and the like.
None of the aforesaid prior art discloses a skin cleanser and skin conditioner or a pre or post-shave/skin conditioner consisting of a low level of a nonionic surfactant as the sole surfactant, a minor amount of an organic acid (or salt thereof) having a pKa from 4.5 to 6.5 to provide a pH of about 4.5 to 6.5, and a major amount of water, which may be thickened with polyethylene glycol--150 distearate to a thick liquid or thickened with an acrylic acid polymer to form a gel, and preferably contains a preservative system.